github.com/axw/juju@v0.0.0-20161005053422-4bd6544d08d4/state/persistence.go (about)

     1  // Copyright 2015 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package state
     5  
     6  import (
     7  	"github.com/juju/errors"
     8  	jujutxn "github.com/juju/txn"
     9  	"gopkg.in/mgo.v2"
    10  	"gopkg.in/mgo.v2/txn"
    11  
    12  	"github.com/juju/juju/state/storage"
    13  )
    14  
    15  // Persistence exposes persistence-layer functionality of State.
    16  type Persistence interface {
    17  	// One populates doc with the document corresponding to the given
    18  	// ID. Missing documents result in errors.NotFound.
    19  	One(collName, id string, doc interface{}) error
    20  
    21  	// All populates docs with the list of the documents corresponding
    22  	// to the provided query.
    23  	All(collName string, query, docs interface{}) error
    24  
    25  	// Run runs the transaction generated by the provided factory
    26  	// function. It may be retried several times.
    27  	Run(transactions jujutxn.TransactionSource) error
    28  
    29  	// NewStorage returns a new blob storage for the environment.
    30  	NewStorage() storage.Storage
    31  
    32  	// ApplicationExistsOps returns the operations that verify that the
    33  	// identified application exists.
    34  	ApplicationExistsOps(applicationID string) []txn.Op
    35  
    36  	// IncCharmModifiedVersionOps returns the operations necessary to increment
    37  	// the CharmModifiedVersion field for the given application.
    38  	IncCharmModifiedVersionOps(applicationID string) []txn.Op
    39  
    40  	// NewCleanupOp creates a mgo transaction operation that queues up
    41  	// some cleanup action in state.
    42  	NewCleanupOp(kind, prefix string) txn.Op
    43  }
    44  
    45  type statePersistence struct {
    46  	st *State
    47  }
    48  
    49  // newPersistence builds a new StatePersistence that wraps State.
    50  func (st *State) newPersistence() Persistence {
    51  	return &statePersistence{st: st}
    52  }
    53  
    54  // One gets the identified document from the collection.
    55  func (sp statePersistence) One(collName, id string, doc interface{}) error {
    56  	coll, closeColl := sp.st.getCollection(collName)
    57  	defer closeColl()
    58  
    59  	err := coll.FindId(id).One(doc)
    60  	if err == mgo.ErrNotFound {
    61  		return errors.NotFoundf(id)
    62  	}
    63  	if err != nil {
    64  		return errors.Trace(err)
    65  	}
    66  	return nil
    67  }
    68  
    69  // All gets all documents from the collection matching the query.
    70  func (sp statePersistence) All(collName string, query, docs interface{}) error {
    71  	coll, closeColl := sp.st.getCollection(collName)
    72  	defer closeColl()
    73  
    74  	if err := coll.Find(query).All(docs); err != nil {
    75  		return errors.Trace(err)
    76  	}
    77  	return nil
    78  }
    79  
    80  // Run runs the transaction produced by the provided factory function.
    81  func (sp statePersistence) Run(transactions jujutxn.TransactionSource) error {
    82  	if err := sp.st.run(transactions); err != nil {
    83  		return errors.Trace(err)
    84  	}
    85  	return nil
    86  }
    87  
    88  // NewStorage returns a new blob storage for the environment.
    89  func (sp *statePersistence) NewStorage() storage.Storage {
    90  	envUUID := sp.st.ModelUUID()
    91  	// TODO(ericsnow) Copy the session?
    92  	session := sp.st.session
    93  	store := storage.NewStorage(envUUID, session)
    94  	return store
    95  }
    96  
    97  // ApplicationExistsOps returns the operations that verify that the
    98  // identified service exists.
    99  func (sp *statePersistence) ApplicationExistsOps(applicationID string) []txn.Op {
   100  	return []txn.Op{{
   101  		C:      applicationsC,
   102  		Id:     applicationID,
   103  		Assert: isAliveDoc,
   104  	}}
   105  }
   106  
   107  // IncCharmModifiedVersionOps returns the operations necessary to increment the
   108  // CharmModifiedVersion field for the given service.
   109  func (sp *statePersistence) IncCharmModifiedVersionOps(applicationID string) []txn.Op {
   110  	return incCharmModifiedVersionOps(applicationID)
   111  }
   112  
   113  // NewCleanupOp creates a mgo transaction operation that queues up
   114  // some cleanup action in state.
   115  func (sp *statePersistence) NewCleanupOp(kind, prefix string) txn.Op {
   116  	return newCleanupOp(cleanupKind(kind), prefix)
   117  }